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At least 1,081 records · Page 60Linked to original sources
PubMed1998

Identification and assessment of endocrine disruptors: limitations of in vivo and in vitro assays.

It has been suggested that chemicals and complex mixtures capable of modulating the endocrine system may contribute to adverse health, reproduction, and developmental effects in humans and wildlife. These effects include increased incidence of hormone-dependent cancers, compromised reproductive fitness, and abnormal reproductive system development. In response to public concern, regulatory agencies in North America and Europe are formulating potential strategies to systematically test chemicals and complex mixtures for their endocrine-disrupting activities. Because of the complexity of the endocrine system and the number of potential endocrine disruptor targets, a tiered approach involving a complementary battery of short- and long-term in vivo and in vitro assays that assesses both receptor and nonreceptor-mediated mechanisms of action is being considered. However, the available established assays use a limited number of end points, and significant information gaps exist for other potential targets in the endocrine system. In addition to discussing the merits and limitations of the assays that may be adopted, this paper also highlights potential problems associated with the use of a tiered testing strategy.

Animals↗
PubMedDate not supplied

[Effects of extremely high-frequency electromagnetic radiation on the immune system and systemic regulation of homeostasis].

Low-intensity of electromagnetic radiation of extremely high frequencies (EHF EMR) is effectively used in medical practice for diagnostics, prevention and treatment of a broad spectrum of diseases of different etiology. However, in spite of existence of many hypotheses about mechanisms of EHF EMR effects on the molecular and cellular levels of organization of living systems, there is not conception that could explain all diversity of the EHF-therapy effects from unified approach. In our opinion, the problem of determination of mechanisms of EHF EMR effects on living organism is divided into two basic tasks: first, determining subcellular structures which can receive radiation, and, second, studying physiological reactions of the organism which are caused by radiation. It is obviously, that investigation of functions of single cells and subcellular elements can not entirely explain therapeutic effects and mechanisms of EHF EMR influence on multicellular organism on the whole. Plenty of functional relationships between organs and systems of organs should be taken into account. In the present review, a realization of the EHF-therapy effects due to the influence on immune system functions and start of system mechanisms of maintenance of the homeostasis on the organism level is hypothesized. Potential targets for EHF EMR acception on the level of different systems of the organism are analysed. The material is formed so that functional relations between immune system and other regulatory systems (nervous and endocrine systems) are traced.

Adaptation, Physiological↗
PubMed2000

Diseases of aging.

By definition, diseases of aging become clinically manifested in elderly patients. However, their pathogenetic basis has to be sought earlier in life. The general thread of this presentation relies on the concept of an evolutionary-Darwinian view of the development of age-related diseases. In essence, this concept states that we may have to "pay" for genetic traits that play a beneficial role earlier in life by the later development of diseases since there is no post-reproductive selective pressure that may have eliminated the potential late onset detrimental effects of such genes. Examples for this kind of trade-off are taken from diseases involving the immune system (infections), the endocrine system (andropause), the nervous system (Alzheimer's disease), the locomoter system (osteoporosis), the cardio-vascular system (atherosclerosis) and cancer.

Adult↗
PubMed2006

Metabolic syndrome and the endocrine stress system.

Obesity constitutes one of the most serious public health problems, with rapidly increasing prevalence in western societies. Consequently, metabolic syndrome, a condition strongly associated with obesity, has become an epidemic problem. Recent studies have implicated chronic alterations to the stress system as playing a major role in the metabolic syndrome's pathophysiology. This brief review discusses the role of stress and hypothalamic-pituitary-adrenal axis dysfunction in the development of metabolic syndrome as well as new insights into the crosstalk between adipose tissue and endocrine stress system.

Adipocytes↗
PubMed2002

The role of vitamin D receptor gene polymorphisms in bone biology.

The role of vitamin D and its receptor (VDR) in skeletal metabolism is well known but the vitamin D endocrine system seems to play an important role in other metabolic pathways as well, such as those involved in osteoarthritis, the immune response and cancer. One approach to understand the vitamin D endocrine system is to study the influence of variations in the DNA sequence of important proteins of this system. For example, deleterious mutations in the VDR gene cause 1,25-dihydroxyvitamin D-resistant rickets, a rare monogenetic disease. More subtle sequence variations (polymorphisms) in the VDR gene occur much more frequently but their effects are poorly understood. Their influence on the vitamin D endocrine system is currently under scrutiny in relation to a number of so-called complex diseases and traits such as osteoporosis. The interpretation of polymorphic variations in the VDR gene is severely hindered by the fact that several of the polymorphisms used have unknown effects. However, current data indicate that dozens of additional polymorphic variations exist in the VDR gene that could each have different types of consequences. Therefore, efforts are focussed on finding novel sequence variations and to study their interaction in molecular- and cell-biological experiments as well as in genomic epidemiological studies. The ultimate goal of this approach is to identify the combinations of functional sequence variants that modulate the vitamin D endocrine system and confer risk of disease.

Bone and Bones↗
PubMed2003

Identification and quantification of bisphenol A by gas chromatography and mass spectrometry in a lab-scale dual membrane system.

Endocrine disruptor contamination is an emerging issue of concern in the field of water quality engineering. In this study, a lab-scale microfiltration (MF) and reverse osmosis (RO) based water reclamation system was set up to monitor and evaluate the removal of bisphenol A (BPA), which is a known oestrogenic compound. The identification and quantification of BPA were performed by using gas chromatography coupled with mass spectrometry. It was noted that the detection method used in this study was able to achieve an average recovery ranging from 88.2 to 94.1% of BPA with standard deviations of less than 10% in different spiked samples. The detection limit of the analytical protocol was determined at 20 ng L(-1). Based on the analytical protocol, it was noted that a low level of BPA (1.18-3.04 microg L(-1)) could be detected in feed water (effluent of an activated sludge treatment system) to the dual membrane water reclamation system. The results obtained suggested that BPA could be easily chlorinated by sodium hypochlorite with a dosage of 4 to 5 mg L(-1) and a contact time of 1 to 2 min. In this lab-scale study, a satisfactory removal of BPA was readily obtained by RO and BPA was abated to an undetectable level in the product water. It was noted that the RO rejection characteristic of BPA was not sensitive to the variations in raw feed water characteristics experienced in this study. In addition, it was noted that BPA concentration present in raw feed water did not exert any significant impact on RO performance in terms of BPA rejection. The results of this study demonstrated that membrane technology could be effectively used for BPA removal.

Benzhydryl Compounds↗
PubMed2004

Endocrine aspects of cancer gene therapy.

The field of cancer gene therapy is in continuous expansion, and technology is quickly moving ahead as far as gene targeting and regulation of gene expression are concerned. This review focuses on the endocrine aspects of gene therapy, including the possibility to exploit hormone and hormone receptor functions for regulating therapeutic gene expression, the use of endocrine-specific genes as new therapeutic tools, the effects of viral vector delivery and transgene expression on the endocrine system, and the endocrine response to viral vector delivery. Present ethical concerns of gene therapy and the risk of germ cell transduction are also discussed, along with potential lines of innovation to improve cell and gene targeting.

Clinical Trials as Topic↗
PubMed1995

Health promotion and exercise training.

Health is determined not only by the absence of disease, but also by an individual's resistance to pathogenic factors. In turn, resistance depends on the effectiveness of specific homeostatic regulation and the mechanism of general adaptation. Through the change in adaptivity, health may be increased or reduced. While it is difficult to predict which specific homeostatic mechanism will be necessary in various stages of life in the individual, it is more reliable to try to improve health, thereby increasing the effectiveness of the mechanism of general adaptation. Physical training results in a variety of changes in individuals. There are several changes which are essential both for increased exercise performance and for increasing adaptivity, by favouring the effectiveness of the mechanism of general adaptation. These changes: improve central nervous regulation and central nervous system functions; increase endocrine system capacity; increase energy potential; improve the capacity of the oxygen transport system; improve oxidation processes; increase metabolic and functional economy; increase functional stability; and increase the number of Na+,K+ -pumps. The influence of these changes on adaptivity is accomplished by the influence of exercise training on immunoactivities, and by the antisclerotic effect of training. The latter may be considered to be metabolic (actualised through the training effect on lipoprotein metabolism and aging-related calcium distribution) or mechanical (protection of tissues from sclerotic changes by their activities) effects. The training effects are specifically dependent upon performed exercises. Endurance exercise is considered to be the most important and widely recommended form of exercise for health improvement. Most of the training benefits (listed above) for increased adaptivity are induced by aerobic endurance training. Gymnastic exercises are indispensable in regard to mechanical antisclerotic effect. They are also essential influences on the central nervous system. Aerobic dance or aerobic rhythmic gymnastics are ways by which the positive effects of endurance and gymnastic exercise can be combined.

Adaptation, Physiological↗
PubMed1986

Non-antisecretory activities of H2 antagonists.

Besides the main effect of the H2 antagonists--that is, the inhibition of gastric acid secretion--these drugs possess several other pharmacological activities, which in most cases may be evident only for doses higher than those required to produce the H2 blockade. The non-secretory activities of the H2 antagonists may be classified into true side effects--that is, those independent of the primary action, which may or may not depend on the primary action. They concern the central and autonomic nervous systems, cardiovascular and endocrine systems, digestive system (gut, liver, pancreas), immune system, and so forth. It is obvious that when the actions of the different H2 blockers are completely at variance with regard to the same factor (cimetidine increase the TSH response to TRH, whereas ranitidine decreases it; ranitidine stimulates gastrointestinal motility, whereas oxmetidine inhibits it; ranitidine increases the exocrine pancreatic response to cholecystokinin, whereas oxmetidine decreases it; metiamide and cimetidine increase the activity of histamine methyltransferase, whereas burimamide decreases it), this is a clear demonstration that we are dealing with non-specific effects rather than with H2-receptor blockade. All these effects may be of interest because sometimes they may be useful in potentiating the primary action, and sometimes they may represent adverse reactions. In any case, they characterize pharmacologically the individual molecules of the family.

Autonomic Nervous System↗
PubMed1993

Endocrine response to HIV infection. Involvement of thyroid gland.

Endocrine dysfunctions were associated at different stages of infection, including those early in the course of HIV infection. In fact adrenal insufficiency, hyporeninemic hypoaldosteronism, hyponatremia, reduced gonadotropins levels, gonadal abnormalities and changes in hormone-binding proteins were reported in HIV infection. Also a thyroid involvement with autoimmune phenomena was observed in HIV infection by several studies giving different explanations of altered thyroid conditions. These findings suggest an effect of HIV on endocrine system. Recognition of endocrine manifestations in these patients may contribute to better characterize different stages of the infection and improve the management of HIV patients.

AIDS-Related Opportunistic Infections↗
PubMed2001

The process of aging changes the interplay of the immune, endocrine and nervous systems.

The immune, endocrine and nervous systems interact with each other by means of cytokines, hormones and neurotransmitters. Interaction is dependent on specific receptors and respective signaling pathways in target cells. During aging, changes occur on many levels of these global systems which depend on oxidative damage, non-enzymatic glycosylation, mitochondrial mutations, defects in cell cycle control, mitotic dysregulation, genome instability, telomere shortening and other chromosomal pathologies. An alteration of the numerical value of a parameter of one system can lead to changes of the numerical value of a variable of another system. In a non-linear dynamic process these changes can contribute to the aging phenotype. Although it is extremely difficult to dissect linear interrelations of three global systems during aging, this review attempts to identify some simple linear pathways. Furthermore, it is demonstrated that chronic inflammatory diseases may accelerate the aging process. This review also reveals that new statistical and computational methods are necessary to unravel the complexity of the aging process.

Aging↗
PubMed2005

The emerging role of the endocannabinoid system in endocrine regulation and energy balance.

During the last few years, the endocannabinoid system has emerged as a highly relevant topic in the scientific community. Many different regulatory actions have been attributed to endocannabinoids, and their involvement in several pathophysiological conditions is under intense scrutiny. Cannabinoid receptors, named CB1 receptor and CB2 receptor, first discovered as the molecular targets of the psychotropic component of the plant Cannabis sativa, participate in the physiological modulation of many central and peripheral functions. CB2 receptor is mainly expressed in immune cells, whereas CB1 receptor is the most abundant G protein-coupled receptor expressed in the brain. CB1 receptor is expressed in the hypothalamus and the pituitary gland, and its activation is known to modulate all the endocrine hypothalamic-peripheral endocrine axes. An increasing amount of data highlights the role of the system in the stress response by influencing the hypothalamic-pituitary-adrenal axis and in the control of reproduction by modifying gonadotropin release, fertility, and sexual behavior. The ability of the endocannabinoid system to control appetite, food intake, and energy balance has recently received great attention, particularly in the light of the different modes of action underlying these functions. The endocannabinoid system modulates rewarding properties of food by acting at specific mesolimbic areas in the brain. In the hypothalamus, CB1 receptor and endocannabinoids are integrated components of the networks controlling appetite and food intake. Interestingly, the endocannabinoid system was recently shown to control metabolic functions by acting on peripheral tissues, such as adipocytes, hepatocytes, the gastrointestinal tract, and, possibly, skeletal muscle. The relevance of the system is further strenghtened by the notion that drugs interfering with the activity of the endocannabinoid system are considered as promising candidates for the treatment of various diseases, including obesity.

Animals↗
PubMed1997

Endocrine disruptor risk characterization: an EPA perspective.

The characterization of risk to endocrine-disruptive agents may prove to be one of the greatest challenges that the risk assessment/regulatory community has ever faced. Why is this so? The endocrine system is actually many systems, having complex interactions and interdependencies. Normal endocrine function is often dependent on cyclical events, rather than steady-state. Timing is everything, as evidenced by significant differences in adverse outcome as a function of age and stage of development. Further, the consequences of concomitant exposures to endocrine-active substances in the diet or as therapeutic agents are poorly understood. So, how should risk characterization to these agents be approached? This presentation will include the description of current practices for addressing hormonally mediated cancer and noncancer effects and offer speculation on modifications to these approaches that might be necessary as our knowledge of this area increases.

Animals↗